Natural gas not only is more economical than petrol and gasoline, but also produces less air pollution in comparison with mentioned fuels; therefore, researchers have more tendencies toward natural gas rather than the others. Using high efficiency engines that run with natural gas solely, necessitates designing more compatible natural gas burner engines. For two reasons, decision makers in automobile industries didn't show intention in manufacturing engines running with natural gas solely. First of all, natural gas is not able to produce power as strong as petrol or gasoline. Secondly, natural gas is not available all over the world.
Researchers, who didn't completely disappointed of usage of natural gas in automobile industry, advise people to convert their petrol fuel system vehicle to bi-fuel by applying some changes. Because of appropriate cost of natural gas, bi-fuel systems became prevalent in some countries but drivers of bi-fuel system vehicles usually complained of power of their automobile engine while their automobile runs with natural gas. They are being forced to switch to petrol fuel instead of natural gas in many cases like Uphill roads, pickup trucks loading and starting in low ambient temperature. Switching to petrol fuel was not desirable and it was averse the goal of bi-fuelling. Among the other deficiencies of bi-fuel system, depreciation of engine due to dryness of natural gas is worthy of mention which diminishes the engine life.